Help with tire sizing, spare?

[UnorthodoxCreat]

I have a 2006 V8 Limited with the auto 4WD. It's all stock except for 22" Ford Edge wheels with 275/40R22 tires. Last weekend we stopped at my in laws on the way to the beach when I noticed a rivet in my right rear tire(who knows how long it's been there). We tried to take it somewhere nearby to get it fixed but they couldn't do it that day. Decided to go back to the house and just put the original spare on. We hit the road and something didn't seem right. Something in the driveline seemed to be binding. I couldn't tell what it was but I was afraid of tearing up something in the driveline, so after less than 10 minutes of driving I stopped in a parking lot and put the tire with the rivet back on. All was good again so we continued our 3 hour trip to the beach, returned home and I've been so busy I've just been driving it and not getting it fixed.

I assumed the noise/feeling in the driveline was from a difference in tire height from the 275/40R22 tires to the spare 235/65R18. I was going to get my bad tire fixed and change the spare to a different size since it's 15 years old anyways but now I'm not so sure that's the answer. Using an online tire calculator shows the 22's being .7" taller. Standing the tires beside each other, any difference in height isn't distinguishable. Any idea what was going on when I had the spare on? Is it the difference in width, 9.3" vs 10.8"? I just checked now and we did have 40psi in the spare tire but I don't think that was enough to matter.

 

[imp]

I have a 2006 V8 Limited with the auto 4WD. It's all stock except for 22" Ford Edge wheels with 275/40R18 tires. Last weekend we stopped at my in laws on the way to the beach when I noticed a rivet in my right rear tire(who knows how long it's been there). We tried to take it somewhere nearby to get it fixed but they couldn't do it that day. Decided to go back to the house and just put the original spare on. We hit the road and something didn't seem right. Something in the driveline seemed to be binding. I couldn't tell what it was but I was afraid of tearing up something in the driveline, so after less than 10 minutes of driving I stopped in a parking lot and put the tire with the rivet back on. All was good again so we continued our 3 hour trip to the beach, returned home and I've been so busy I've just been driving it and not getting it fixed.

I assumed the noise/feeling in the driveline was from a difference in tire height from the 275/40R18 tires to the spare 235/65R18. I was going to get my bad tire fixed and change the spare to a different size since it's 15 years old anyways but now I'm not so sure that's the answer. Using an online tire calculator shows the 22's being .7" taller. Standing the tires beside each other, any difference in height isn't distinguishable. Any idea what was going on when I had the spare on? Is it the difference in width, 9.3" vs 10.8"? I just checked now and we did have 40psi in the spare tire but I don't think that was enough to matter.

How did you put 18-inch tires on 22-inch wheels??

 

[UnorthodoxCreat]

How did you put 18-inch tires on 22-inch wheels??

Typo, sorry, it's fixed.

 

[Rcflyer330]

On any awd or 4x4 vehicle all tires must be the same overall diameter as all of the others.
What happens is what you experienced and it binds the drivetrain due to how the system works. If you leave it that way you will cause damage to the drivetrain.

If you change tire sizes you must change the spare tire to a diameter that matches the new tire size or your spare becomes dead weight and is useless.

What you need to do is find out the spare rim diameter and them find a tire that matches the overall diameter of your normal tire. I do not know how much difference in the diameter is acceptable but i do know its not much. For example if you have to replace your tire with new one may require you to replace all 4 tires due to the difference in diameters or the drivetrain may bind up.

 

[J_C]

When you stood the tires next to each other, did you have the 275 installed so the weight of the vehicle was decreasing its height?

Anything in an 18" will be off by 0.7% or more, what if you picked up a spare 22" rim from a junkyard, get same size already on the vehicle, and if you can get a matching Ford Edge wheel then you can even put the tire into the rotation, unless there's already too much wear on your tires or you can't find a used tire with similar wear or get a shop to shave it down for you. However with the 275's worn, you might find that a new 245/65R18 is pretty close, at least closer than you are now.

No it isn't going to be the width. Higher PSI in the spare could only have helped to make it a slightly larger rolling diameter, closer to the others but apparently not enough.

 

[UnorthodoxCreat]

I understand all tires need to be the same diameter. I don't know what the tolerance is for difference in height but based on this experience I'd say it's less than I expected. I did have the 275s on the vehicle when I was comparing height visually so I hadn't thought about that but it would certainly help hide the difference in height. A 245/65R18 or 265/60R18 are 30.5" tall so that might be a possibility. I could buy a spare 22" rim but I hate to spend so much money on a rim I'll never see. I could replace one of my wheels that has the most rash on it but I would have to swap one of my old tires on to it versus new because my 22" tires are definitely in the later stages of their life. I'll be lucky to get another year out of them before they need replaced. Cheapest matching wheel I see that isn't rashed terrible is about $300 on ebay plus I'll need a new tire for it. Hate to spend $500+ on something I hope to never use but I got lucky this time. I guess I'd be glad I spent the money if I really needed it.

 

[J_C]

^ I'd check local junkyards for rims, here one wants $20 + $15 core for alloys. Even if you have to pay a distant yard to ship it, will probably be a lot cheaper than $300.